Methods of making belts of the kind defined initially and corresponding apparatus are known. Conveyor or process belts must meet extremely high demands as regards resistance to abrasion and wear as well as structural strength. In the past, rubber was the material most frequently used for such belts. Nowadays, however, polyurethane materials are preferred because of the above mentioned high requirements in respect of abrasion resistance and structural strength. A core, especially a multiple core is integrated in the belt as a carrier or bearer of tensions in order that the tendency of elongation of belts made of such materials may be kept within reasonable limits. These tension bearers may be embodied by fabric mats, cord filaments, or steel wires.
A particular field of application of process belts are the so-called separators. They are machines used in the foodstuffs industry for separating such items as meat and fish from bones, cheese from its rind, and even bananas from their peel. The material to be separated, for instance bones with meat still on them, is fed under high pressure between a squeezing or process belt and a drum having a perforated circumferential surface. The substances to be yielded with preference, such as the meat, fish, cheese, or bananas are collected inside the drum in mashed form, while the wastage, such as bones and peels and the like accumulate outside of the drum. In view of the fact that the process belts used in such separators come into contact with foodstuffs, they must not be subject to wear and abrasion and be very robust and sturdy. Consequently it is particulary important that the process belt be made of an abrasion resistant material, such as polyurethane and that the elongation of the belt be restricted by a tension bearer incorporated in the belt.
It is a disadvantage of known methods of the kind mentioned above that it is not possible in making endless belts by centrifugal casting or displacement casting methods to place the core as the carrier of tension in the belt in such a position that it will be enclosed uniformly all around by the cast material. What is known, for instance, is a method of making toothed belts which include cord filaments or steel wires as the tension bearer which is wound around a center portion provided with the teeth. This has the disadvantage that, upon casting, the tension bearer is located at the base of the teeth in the region of the inner circumference of the toothed belt.